Mechanistic aspects of the photodynamic inactivation of Candida albicans induced by cationic porphyrin derivatives.

EZEQUIEL D. QUIROGA, M. PAULA CORMICK, PATRICIA PONS, M. GABRIELA ALVAREZ AND EDGARDO N. DURANTINI.

EUROPEAN JOURNAL OF MEDICAL CHEMISTRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2012 vol. 58 p. 332 - 339

0223-5234

Photodynamic inactivation of Candida albicans produced by 5-(4-trifluorophenyl)-10,15,20-tris(4-N,N,Ntrimethylammoniumphenyl) porphyrin (TFAP3+), 5,10,15,20-tetrakis(4-N,N,N-trimethylammoniumphenyl) porphyrin (TMAP4+) and 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin (TMPyP4+) was investigated to obtain insight about the mechanism of cellular damage. In solution, absorption spectroscopic studies showed that these cationic porphyrins interact strongly with calf thymus DNA. The electrophoretic analysis indicated that photocleavage of DNA induced by TFAP3+ took place aft er long irradiation periods (>5 h). In contrast, TMAP4+ produced a marked reduction in DNA band after 1 h irradiation. In C. albicans, these cationic porphyrins produced a 3.5 log decrease in survival when the cell suspensions (107 cells/mL) were incubated with 5 mM photosensitizer and irradiated for 30 min with visible light (fluence 162 J/cm2). After this treatment, modifications of genomic DNA isolated fromC. albicans cells were not found by electrophoresis. Furthermore, transmission electron microscopyshowed structural changes with appearance of low density areas into the cells and irregularities in cellbarriers. However, the photodamage to the cell envelope was insufficient to cause the release of intracellular biopolymers. Therefore, modifications in the cytoplasmic biomolecules and alteration in the cell barriers could be mainly involved in C. albicans photoinactivation.